CD response to vibration during playback of a CD

ABSTRACT

A system and methods for evaluating the response of an optical digital disk player to vibration encountered during playback of optical digital disks are provided. The system includes a simulator configured to provide digital simulated output signals simulating the output of an optical digital disk player encountering vibration during playback of an optical digital disk. The system also includes digital-to-analog converter circuitry to convert the digital simulated output signals to analog simulated output signals and provide the analog simulated output signals to processing circuitry. The processing circuitry generates control signals based on the value of the analog simulated output signals, and provides the control signals as outputs.

RELATED APPLICATION

This application is a Reissue of U.S. application Ser. No. 11/542,956(filed Oct. 4, 2006), now U.S. Pat. No. 7,668,058 (issued Feb. 23,2010).

TECHNICAL FIELD

The present invention is generally directed to optical digital diskplayer testing systems and methods, and, more specifically, to a systemand method for testing the response of optical digital disk players tovibration encountered during playback of optical digital disks.

BACKGROUND OF THE INVENTION

Optical digital disk players, such as, for example, audio compact disk(CD) players, are frequently employed in automobiles as a means forproviding audio entertainment to vehicle occupants. To enhance thelistening experience of vehicle occupants, CD players are typicallydesigned to compensate for anomalies that can be encountered during theaudio CD playback process that might otherwise act to interrupt and/ordistort the audio produced during the CD playback process. Examples ofanomalies that can be encountered during the CD playback process includedefects on the CD itself, such as, for example, scratches, smudges,spots, manufacturing defects and/or dirt located on the surface of theCD. Other anomalies that can be encountered during the audio CD playbackprocess include physical shocks and vibrations introduced into the CDplayer. While anomalies on the surface of audio CDs are not unique tothe automotive environment, and can also impact the playback of audioCDs in home or portable CD systems, shock and vibration can beespecially prevalent and problematic in an automotive environment inwhich a vehicle is often traveling at a high rate of speed over a roughroad surface.

The anomalies discussed above can act to prevent the pickup mechanism ofthe CD player from accurately reading and/or interpreting data stored onthe CD. In order to reduce the negative impact of such anomalies on thequality of playback, CD player components, including the pickupmechanism and CD player processing circuitry, are typically designed toadapt to anomalies as they are encountered during the playback process.FIG. 1 generally illustrates components typically included in aconventional CD player 20. CD player 20 includes a laser diode (notshown) for projecting a light beam on a surface of a CD 50 placed in theCD player 20. CD player 20 also includes a pickup mechanism 22 forreading signals from the CD 50 and providing them to additionalcircuitry in the CD player 20 for processing. As shown, pickup mechanism22 includes a photosensor 11, sled adjustment mechanism 18, trackingadjustment mechanism 14 and focus adjustment mechanism 16. Sledadjustment mechanism 18, tracking adjustment mechanism 14, and focusadjustment mechanism 16 are configured to control the position of pickupmechanism 22 relative to the surface of CD 50. Photosensor 11 includesan array of photo diodes 2, 4, 6, 8, 10 and 12 for detecting lightreflected from the surface of the CD 50 and providing analog outputsignals indicative of the light received by the photo diodes 2, 4, 6, 8,10 and 12. Photo diodes 10 and 12 are configured to determine thetracking status of pickup mechanism 11. Photo diodes 2, 4, 6, and 8 areconfigured to read audio data and, in addition, provide signalsindicative of the focus status of pickup mechanism 11. Pickup mechanism22 is configured to be positioned relative to CD 50 by sled adjustmentmechanism 18, tracking adjustment mechanism 14 and focus adjustmentmechanism 16 in order to accurately read data contained on CD 50.

As shown, the output signals of photo diodes 2 and 6 are combined into afirst combined output signal of photo sensor 11, while the outputsignals of photo diodes 4 and 8 are combined into a second combinedoutput signal of photosensor 11. The first combined output signal,second combined output signal, and output signals provided by trackingphoto diodes 10 and 12 are shown provided to Audio/data processingcircuitry 30 of CD player 20 for processing. Audio/data processingcircuitry 30 is configured to extract high-frequency (HF) audio, focus,and tracking data from the output signals provided by photosensor 11 ofpickup mechanism 22. Audio/data processing circuitry 30 is configured toprovide audio and/or data to circuitry external to audio/data processingcircuitry 30 (not shown) for processing. Audio/data processing circuitry30 processes extracted HF audio data to provide audio signals that areultimately provided as audio output to users of the CD player 20.Audio/data processing circuitry 30 is also configured to process focusand tracking data from photosensor 11 to evaluate the operation ofpickup mechanism 22 and generate control signals based on the focus andtracking data. The control signals generated by audio/data processingcircuitry 30 are provided to drive motor 46, and to sled adjustmentmechanism 18, tracking adjustment mechanism 14, and focus adjustmentmechanism 16 of pickup mechanism 22, and are used to control thosedevices to optimize the quality of audio/data output provided by CDplayer 20 during playback of a CD 50. As shown, the control signalsinclude motor control signals M1, focus control signals F1, trackingcontrol signals T1, and sled control signals S5.

One conventional method typically used to optimize how the CD player 20generally illustrated in FIG. 1 responds to anomalies is to monitor theaudio/data output of the CD player 20 for skip and/or mute conditionsduring an anomaly that occurs during playback of a CD 50. A skipcondition is a condition in which the audio output of a CD player 20that is playing an audio program is muted for a period of time due to ananomaly (such as, for example, a vibration or scratch), after whichperiod of time the audio output of the CD player 20 resumes at adifferent point in the audio program than when the mute first occurred.This effectively results in audio material of the CD being skipped as aresult of the anomaly, and is generally an undesirable condition. A mutecondition is similar to a skip condition, with the main difference beingthat the CD player 20 resumes playback of the audio program at the samepoint where the mute first occurred. While undesirable, this conditionis less problematic than a skip condition, because little to no audiomaterial is omitted during playback. CD player system designerstypically attempt to design a system in which skip and or muteconditions are avoided in spite of the occurrence of anomalies duringplayback of a CD 50.

As noted above, anomalies can include defects in the disk itself, orenvironmental factors to which the CD player is exposed during playback.For example, in order to monitor the components and/or signals during a“disk defect” anomaly, a CD played in a CD player 20 may be a test CDincluding defects on the disk surface, such as scratches and/or dirt.When the CD player 20 encounters these defects on the test CD, theaudio/data signals are monitored to determine how well the CD player 20responds to the given anomaly. In order to monitor the performance ofcomponents and/or signals during an “environmental” anomaly, such asvibration, the CD player 20 is vibrated while a CD 50 is played. Bymonitoring the audio/data signals while the CD player 20 is beingvibrated, the response of the CD player 20 to the vibration isdetermined.

Once the response of the CD player 20 to anomalies has been determined,changes and/or adjustments are made to components and/or circuitry ofthe CD player 20 in order to attempt to improve the response of the CDplayer 20 to anomalies. Once changes have been made, the CD player 20can again be operated in the presence of anomalies, and the audio/datasignals monitored to determine if further adjustments are needed tofurther improve the system performance. In this iterative manner,components and circuitry of CD player 20 can be adapted to provide animproved listening experience for the user of the CD player.

While the aforementioned conventional approach of generating anomaliesby means of CDs having defects (test CDs) or by means of physicallymanipulating the CD player by introducing physical shocks and/orvibrations can provide useful information for optimization of the CDplayer design, it does have drawbacks. For example, test CDs designed tohave specific defects for use in CD player testing can be expensive, andare typically subject to breakdown over periods of repeated use,requiring the purchase of additional expensive testing CDs. In addition,physically vibrating and/or manipulating the CD player while it isplaying a CD during repeated testing iterations can expose both the testCD and CD player itself to physical damage. Finally, the need to swapmultiple test CDs having various defects in and out of a CD player 20during iterative test cycles can be time consuming and labor intensive.

What is needed is a CD player testing system and method that reduces thedependence on test CDs and physical manipulation of the CD player beingtested, and that reduces the need for repeated insertion and removal oftest CDs during iterative test cycles.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a system forevaluating the response of optical digital disk player components tovibration during playback of an optical digital disk is provided. Thesystem includes a simulator configured to generate a digital simulatedoutput signal simulating an output of an optical digital disk playerexperiencing vibration during playback of an optical digital disk. Thesystem also includes a digital-to-analog converter coupled to thesimulator and configured to convert the digital simulated output signalto an analog simulated output signal, and processing circuitry coupledto the digital-to-analog converter and configured to receive the analogsimulated output signal from the digital-to-analog converter. Theprocessing circuitry provides control signals as outputs based on thevalue of the analog simulated output signal.

In accordance with another aspect of the present invention, a method forevaluating the response of an optical digital disk player to vibrationencountered during playback of an optical digital disk is provided. Themethod includes the steps of coupling simulator circuitry to processingcircuitry configured to process signals from an optical digital diskplayer pickup mechanism, and creating in the simulator circuitry asimulated anomaly signal simulating anomaly waveform characteristicsprovided by an optical digital disk player encountering vibration duringplayback of an optical digital disk. The method further includes thesteps of providing the simulated signal to the processing circuitry andprocessing the simulated signal in the processing circuitry to generateat least one control signal.

In accordance with still another aspect of the present invention, amethod for evaluating the response of audio compact disk playercircuitry to vibration encountered during playback of an audio compactdisk is provided. The method includes the steps of coupling simulatorcircuitry to processing circuitry configured to process signals providedby an audio compact disk player. The method also includes the step ofcreating in the simulator circuitry a simulated anomaly signalsimulating waveform characteristics provided as an output signal by apickup mechanism of an audio compact disk player encountering vibrationduring playback of an audio compact disk. The method further includesthe steps of providing the simulated signal to the processing circuitry,processing the simulated anomaly signal in the processing circuitry togenerate at least one control signal that is a function of the simulatedanomaly signal, and monitoring the at least one control signal toevaluate the response of the processing circuitry to the simulatedanomaly signal.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a block diagram of a conventional CD player that is generallyknown;

FIG. 2 is a block diagram generally illustrating an optical digital disktest system, according to one embodiment of the present invention;

FIG. 3 is a flow diagram generally illustrating a first embodiment of amethod for testing an optical digital disk player, according to thepresent invention; and

FIG. 4 is a flow diagram generally illustrating a second embodiment of amethod for testing an optical digital disk player, according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although the preferred embodiments are directed to audio CDs and audioCD players, it should be appreciated that the present invention appliesgenerally to other optical digital disks and optical digital diskplayers. Examples of other media and players to which the invention isdirected include, for example, DVDs and DVD recorders and/or players,writeable and rewriteable CDs and writers/players, and other opticaldigital disks configured to store digital data on a disk and theassociated players.

Referring to FIG. 2, a system 70 for evaluating the response of anoptical digital disk player to anomalies is generally illustrated,according to one embodiment of the present invention. In the presentembodiment, the system 70 includes a simulator 60 having logic 62,memory 63, and at least one algorithm 66 located in the memory 63. Thelogic 62 is configured to operate responsive to the algorithm 66 storedin the memory 63 of simulator 60 to monitor signals, process signals,and generate simulated signals. In the present embodiment, simulator 60is a computer. It should be appreciated that in an alternate embodiment,simulator 60 could be implemented in a hardware-only configuration,without software. In the present embodiment, the simulated signalsgenerated by simulator 60 are digital simulated signals. In an alternateembodiment, the simulated signals may be analog signals.

Simulator 60 is shown coupled to high-speed digital-to-analog convertercircuitry 68. High-speed digital-to-analog converter circuitry 68 isconfigured to receive digital simulated signals from simulator 60,convert the digital simulated signals to analog simulated signals, andprovide the resulting analog simulated signals to circuitry coupled tohigh-speed digital-to-analog converter circuitry 68. In the presentembodiment, simulator 60 is also shown coupled to analog-to-digitalconverter circuitry 61, which is also coupled to audio/data processingcircuitry 30. Analog-to-digital converter circuitry 61 is configured toreceive electrical control signals from audio/data processing circuitry30, convert the received control signals to digital signals, and providethe digital control signals to simulator 60. In an alternate embodiment,audio/data processing circuitry 30 may provide control signals directlyto simulator 60.

As noted above, simulator 60 is configured to generate digital simulatedsignals. The digital simulated signals provided by simulator 60 tohigh-speed digital-to-analog converter circuitry 68 are configured tosimulate photo diode signals that would be provided by photodiodes 2-12of photosensor 11 of CD player 20 of FIG. 1 that is playing a CD 50during the occurrence of an anomaly. In one exemplary embodiment, theanomaly is a disk defect, and the digital simulated signals provided bysimulator 60 are configured to simulate signals provided by a CDphotosensor 11 when a test CD 50 having a defect is being played back bythe CD player 20 of FIG. 1. In another exemplary embodiment, the anomalyis a physical shock introduced into the CD player 20 of FIG. 1, and thedigital simulated signals provided by simulator 60 are configured tosimulate the output of a CD photosensor 11 when a CD player 20 of FIG. 1playing a CD 50 is exposed to a physical shock, such as, for example, avibration. In the present embodiment, the digital simulated photosensorsignals are created by an algorithm 66 running on simulator 60, and arecreated based on photosensor data provided by a CD player 20 of FIG. 1operating under anomaly conditions. In operation, high-speeddigital-to-analog converter circuitry 68 receives the digital simulatedphotosensor signals, and converts them into analog simulated photosensorsignals. The resulting waveforms of the analog simulated photosensorsignals closely match the analog waveforms of actual photosensor signalsthat would be provided by a photosensor of a CD player 20 of FIG. 1playing a CD 50 in an anomaly condition.

In one embodiment of the present invention, four simulated photosensorsignals, designated as S1-S4 in FIG. 2, are shown provided by simulator60 to high-speed digital-to-analog converter circuitry 68. A firstsimulated photosensor signal S1 simulates the combined output of the twophoto diodes 2 and 6 in the photosensor 11 of CD player 20 of FIG. 1during an anomaly condition. The photo diodes 2 and 6 that are simulatedare photo diodes normally providing an output signal representative ofboth the focus condition of the photosensor 11 of FIG. 1, and audio datadetected by the photo diodes 2 and 6 of the photosensor 11.

The second simulated signal S2 provided by simulator 60 to high-speeddigital-to-analog converter circuitry 68 is a signal simulating thecombined output of two additional photo diodes 4 and 8 in photosensor 11of CD player 20 of FIG. 1 during an anomaly condition. These twoadditional photo diodes 4 and 8 in photosensor 11 of CD player 20normally provide a combined output signal representative of both thefocus condition of the photosensor and audio data detected by the photodiodes 4 and 8 of photosensor 11 of FIG. 1.

The third simulated signal S3 provided by simulator 60 to high-speeddigital-to-analog converter circuitry 68 is a simulated signalrepresenting the output of a fifth photo diode 10 in a photosensor 11 ofCD player of FIG. 1 during an anomaly condition. This fifth photo diode10 provides a signal that is representative of the tracking condition ofthe photosensor 11 of the CD player 20.

The fourth simulated signal S4 provided by simulator 60 to high-speeddigital-to-analog converter circuitry 68 is a signal simulating theoutput of a sixth photo diode 12 in a photosensor 11 of CD player 20 ofFIG. 1 during an anomaly condition. This fourth simulated signal S4 isindicative of the tracking state of the photosensor 11 of the CD player20.

As noted above, high-speed digital-to-analog converter circuitry 68receives the digital simulated signals S1-S4 from simulator 60, andconverts the digital simulated signals into analog simulated signalsS1-S4. After the analog simulated signals S1-S4 have been converted intoanalog signals, the signals closely approximate the analog outputwaveforms of photodiodes 2-12 of photosensor 11 of a CD player 20 ofFIG. 1 that is playing a CD in an anomaly condition. The first andsecond analog simulated signals S1 and S2 include both focus errorinformation and audio information, while the third and fourth analogsimulated signals S3 and S4 include tracking error information.

The analog simulated signals S1-S4 are shown input to audio/dataprocessing circuitry 30. In the present embodiment, audio/dataprocessing 30 is processing circuitry configured to process audio anddata signals provided by an audio CD player pickup mechanism. In analternate embodiment, audio/data processing circuitry 30 is processingcircuitry configured to process audio and/or data provided by otheroptical digital disk player pickup mechanisms. Audio/data processingcircuitry 30 includes comparator circuitry 33, comparator circuitry 35,audio processing circuitry 36, control signal processing circuitry 38,digital-to-analog converter circuitry 40, and data output circuitry 42.As shown, the first and second analog simulated signals S1 and S2containing focus and audio information are processed by comparator 33and audio processing circuitry 36 after being received by audio/dataprocessing circuitry 30. The signals processed by audio processingcircuitry 36 are HF audio signals formed by combining the firstsimulated analog signal S1 with the second simulated analog signal S2prior to providing the resulting HF audio signal to audio processingcircuitry 36. Audio processing circuitry 36 processes the HF audiosignal formed by combining the first simulated analog signal S1 with thesecond simulated analog signal S2 to extract audio information such as,for example, music. Audio processing circuitry 36 is also shown coupledto data output circuitry 42. The audio information provided by audioprocessing circuitry 36 is provided to data output circuitry 42, wherethe audio information is additionally processed and provided toadditional circuitry (not shown) to convert the audio information into aformat that can be perceived by the human ear.

The first and second simulated analog signals S1 and S2 are also inputto comparator circuitry 33 of processing circuitry 30. Comparatorcircuitry 33 compares the value of the first and second simulated analogsignals S1 and S2 to determine if they are indicative of a photosensor11 of FIG. 1 that is out of focus. If the difference between the firstand second simulated analog signals S1 and S2 is approximately zero,there is little or no focus error, and focus adjustment of the pickupmechanism 22 of the CD player 20 of FIG. 1 is not necessary. If however,there is a difference between the values of the first simulated analogsignal S1 and second simulated analog signal S2, a focus error ispresent, indicating that adjustment of the pickup mechanism 22 of the CDplayer 20 may be necessary.

High-speed digital-to-analog converter circuitry 68 is also shownproviding third and fourth simulated analog signals S3 and S4 to audiodata processing circuitry 30. More specifically, third and fourthsimulated analog signals S3 and S4 are provided to comparator circuitry35 of audio/data processing circuitry 30, and are compared to determineif there is a difference between the two signals S3 and S4. If there isno difference between the third and fourth simulated analog signals S3and S4, there is little or no tracking error, and adjustment of thepickup mechanism 22 of the CD player 20 of FIG. 1 is unnecessary. If,however, there is a difference between the value of the third and fourthsimulated analog signals S3 and S4, a tracking error is present, and anadjustment of pickup mechanism 22 of the CD player 20 may be necessary.

Audio/data processing circuitry 30 is also shown including controlsignal processing circuitry 38. Control signal processing circuitry 38is electrically coupled to comparator circuitry 35 and comparatorcircuitry 33. Control signal processing circuitry 38 is also shownreceiving the HF audio signal that is provided to audio processingcircuitry 36. Control signal processing circuitry 38 is configured toprocess an electrical signal received from comparator circuitry 35 todetermine, based on the value of that signal, if there is a trackingerror detected by photosensor 11 of pickup mechanism 22 of the CD player20 of FIG. 1. If control signal processing circuitry 38 determines,based on a tracking error signal received from comparator circuitry 35,that there is a tracking error present, control signal processingcircuitry 38 generates a tracking control signal T1. In the presentembodiment, control signal T1 is configured to control a trackingadjustment mechanism of an optical digital disk player, such as, forexample, tracking adjustment mechanism 14 of pickup mechanism 22 of CDplayer 20 of FIG. 1, to adjust the tracking of the optical digital diskplayer.

Control signal processing circuitry 38 is also shown receiving a focuserror signal from comparator circuitry 33. Control signal processingcircuitry 38 is configured to evaluate the focus error signal receivedfrom comparator circuitry 33 to determine if a focus error is present.If control signal processing circuitry 38 determines that a focus erroris present, control signal processing circuitry 38 generates a focuscontrol signal F1. In the present embodiment, control signal F1 isconfigured to control a focus adjustment mechanism of an optical digitaldisk player, such as, for example, focus adjustment mechanism 16 ofpickup mechanism 22 of CD player 20 of FIG. 1, to adjust the focus ofthe optical digital disk player.

Control signal processing circuitry 38 is also shown receiving an HFaudio signal that has been provided to audio/data processing circuitry30 by high-speed digital-to-analog converter circuitry 68. Controlsignal processing circuitry 38 evaluates the HF audio signal alone, orin combination with, other signals, such as the focus error signal fromcomparator circuitry 33 and/or the tracking error signal from comparatorcircuitry 35, to additionally evaluate whether focus, tracking, or othererrors are present.

In addition to providing the control signals discussed above withrespect to tracking adjustment and focus adjustment, control signalprocessing circuitry 38 is also configured to generate a sled adjustmentcontrol signal S5. In the present embodiment, control signal S5 isconfigured to control a sled adjustment mechanism of an optical digitaldisk player, such as, for example, sled adjustment mechanism 18 ofpickup mechanism 22 of CD player 20 of FIG. 1. Finally, control signalprocessing circuitry 38 is also configured to generate motor controlsignals M1. In the present embodiment, control signal M1 is configuredto control the speed and direction of rotation of a spindle drive motor,such as, for example, spindle drive motor 46 of CD player 20 of FIG. 1.

Audio/data processing circuitry 30 is also shown having I/O circuitry 42for allowing control signals and/or data to be provided to audio/dataprocessing circuitry 30 from external circuitry (not shown), and toallow data and/or control signals to be provided to external circuitry(not shown) from audio/data processing circuitry 30. I/O circuitry 42 isshown coupled to control signal processing circuitry 38, audioprocessing circuitry 36, comparator circuitry 33, and comparatorcircuitry 35. In this manner, HF audio signals, focus error signalsprovided by comparator circuitry 33, tracking error signals provided bycomparator circuitry 35, and control signals provided by control signalprocessing circuitry 38 may be monitored by external circuitry coupledto audio/data processing circuitry 30 via I/O circuitry 42. Audio and/orother data provided via I/O circuitry 42 may also be monitored for skipconditions, mute conditions, and other conditions of interest to a userto evaluate how the processing circuitry 30 responds to variousanomalies.

Control signal processing circuitry 38 is also shown coupled todigital-to-analog converter circuitry 40. As shown, digital-to-analogconverter circuitry 40 receives digital control signals M1, F1, T1 andS5 provided by control signal processing circuitry 38, and converts thedigital control signals into analog control signals before providingthose signals as an output from audio/data processing circuitry 30 toadditional circuitry coupled to audio/data processing circuitry 30.

In the present embodiment, the system 70 is also shown including drivercontrol circuitry 44 coupled to audio/data processing circuitry 30. Asshown, driver control circuitry 44 is configured to receive controlsignals provided by audio/data processing circuitry 30, and convertthose control signals into analog signals that can be directly used bythe devices to which those signals are provided. As shown, drivercontrol circuitry 44 receives four signals from digital-to-analogconverter circuitry 40 of audio/data processing circuitry 30. Thesesignals include motor control signals M1, focus control signals F1,tracking control signals T1, and sled control signals S5. The motorcontrol signals M1 provided by digital-to-analog circuitry 40 ofaudio/data processing circuitry 30 are received by driver circuitry 44and converted to signal levels and formats directly usable by a spindledrive motor, such as, for example, spindle drive motor 46 of FIG. 1, tocontrol the direction and speed of rotation of spindle drive motor 46.

Driver control circuitry 44 is also shown receiving tracking controlsignals T1 from digital-to-analog converter circuitry 40 of audio/dataprocessing circuitry 30. Driver control circuitry 44 converts thereceived analog tracking control signals T1 into control signalsconfigured to be directly used to control a tracking adjustmentmechanism, such as, for example, tracking adjustment mechanism 14 ofpickup mechanism 22 of FIG. 1, to control the tracking of pickupmechanism 22.

Driver control circuitry 44 is also shown receiving focus controlsignals F1 from digital-to-analog converter circuitry 40 of audio/dataprocessing circuitry 30. Driver control circuitry 44 receives the analogfocus control signals F1, converts the focus control signals F1 intosignals configured to be directly used to control a focus adjustmentmechanism, such as, for example, the focus adjustment mechanism 16 ofpickup mechanism 22 of FIG. 1, to control the focus of pickup mechanism22.

Driver circuitry 44 is also shown receiving analog sled control signalsS5 from digital-to-analog converter circuitry 40 of audio/dataprocessing circuitry 30. Driver circuitry 44 converts the receivedanalog sled control signals S5 into sled control signals S5 configuredto be directly used to control the operation of a sled adjustmentmechanism, such as sled adjustment mechanism 18 of pickup mechanism 22of FIG. 1, to control the position of pickup mechanism 22.

In the present embodiment, the control signals M1, F1, T1 and S5,configured as discussed above, are provided as inputs toanalog-to-digital converter circuitry 61, where they are converted intodigital form. In an alternate embodiment, the control signals M1, F1, T1and S5 are provided directly from audio/data processing circuitry 30 toanalog-to-digital converter circuitry 21, without first passing throughdriver circuitry 44. In still another embodiment, the control signalsM1, F1, T1 and S5 are provided directly from audio/data processingcircuitry 30 to simulator 60 without passing through driver circuitry 44or analog-to-digital converter circuitry 61.

In the present embodiment, simulator 60, in addition to being configuredto provide the digital simulated signals discussed above, is alsoconfigured to simulate a response of a tracking adjustment mechanism,focus adjustment mechanism, sled adjustment mechanism, and spindle drivemotor to the control signals T1, F1, S5, and M1, respectively, providedby analog-to-digital converter circuitry 61. In this manner, simulator60 can determine how tracking adjustment mechanisms, focus adjustmentmechanisms, sled adjustment mechanisms, and spindle drive motors ofoptical digital disk players would likely respond to the control signalsgenerated by processing circuitry 30. Based on the determination,adjustments can be made to the processing circuitry 30 to obtain thedesired response.

In addition to monitoring the simulated response of the mechanisms andmotors as described above, simulator 60 is also configured to monitorthe control signals T1, F1, S5 and M1 provided by analog-to-digitalconverter circuitry 61. By monitoring these control signals, simulator60 can determine how processing circuitry 30 is responding to thesimulated digital input. By comparing the values of the control signalswith the desired values, adjustments can be made to processing circuitry30 such that the desired control signals occur based on certainsimulated digital inputs.

Finally, in addition to being able to monitor both the values of thecontrol signals and the simulated response of the mechanism and motorsto the control signals, simulator 60 is also configured to alter thesimulated digital signals it is creating based on the simulated responseof the mechanism and motors, the values of the control signals, or both.In this manner, real time feedback based on the control signalsgenerated by signal processing circuitry 30 and their impact onsimulated mechanism and motors can be used to dynamically adjust thesimulated digital signals to help determine the optimal characteristicsof signal processing circuitry 30.

In this manner, simulator 60 monitors the response of the controlsignals T1, M1, S5 and F1 to the simulated input signals S1-S4 providedby simulator 60. Simulator 60 can use the monitored values of thecontrol signals to alter the values of the simulated signals S1-S4provided to audio/data processing circuitry 30 by simulator 60 viahigh-speed digital-to-analog converter circuitry 68.

In operation, simulator 60 runs a software algorithm 66, which causessimulator 60 to generate digital simulated waveform signals S1-S4.Simulated waveform signals S1-S4 are representative of photo diodesignals that would be provided by a photosensor 11 of the CD player 20of FIG. 1 if the CD player 20 encountered an anomaly during the playbackof a CD 50. It should be appreciated that algorithm 66 may be configuredsuch that a single anomaly is simulated, multiple anomalies aresimulated sequentially, or multiple anomalies are simulatedsimultaneously by simulator 60.

The simulated digital waveform signals S1-S4 are converted into analogsimulated waveform signals S1-S4 by high-speed digital-to-analogconverter circuitry 68. Simulated analog waveform signals S1-S4 are thenprovided to audio/data processing circuitry 30 for additionalprocessing. The simulated analog waveform signals S1-S4 are used toprovide HF audio signals, which are decoded by audio processingcircuitry 36 to provide audio signals for a user of the system. Thesimulated analog waveform signals are also used to extract focus errorinformation and tracking error information indicative of whether thereis a focus and/or tracking error based on the simulated analog waveformsignal. The HF audio focus error and tracking error signals are providedto control signal processing circuitry 38, which evaluates the signalsto determine if there is a focus error, tracking error, and/or othererror based on the received simulated analog signals.

Control signal processing circuitry 38 generates control signals tocorrect identified errors. These control signals include motor controlsignals M1 configured to control the speed and direction of a drivemotor of an optical digital disk player, focus control signals F1configured to control a focus adjustment mechanism of an optical digitaldisk player, tracking control signals T1 configured to control atracking adjustment mechanism of an optical digital disk player, andsled control signals S5 configured to control a sled adjustmentmechanism of an optical digital disk player. These control signals areconverted from digital to analog form by digital-to-analog convertercircuitry 40, processed by driver circuitry 44 to convert the signals toformats capable of controlling other components of CD player 20 of FIG.1, and then provided to simulator 60.

Simulator 60 monitors the values of the focus control signals F1,tracking control signals T1, sled control signals S5, and motor controlsignals M1 to evaluate the response of processing circuitry 30 to thesimulated signals S1-S4 provided by algorithm 66. Simulator 60 may alsoadjust the value of the simulated signals S1-S4 provided by algorithm 66based on the value of the monitored control signals F1, T1, M1 and S5.In addition, simulator 60 simulates the response of the variousmechanisms and motors to the control signals F1, T1, M1 and S5, monitorsthese simulated responses, and adjusts the value of the simulatedsignals S1-S4 provided by algorithm 66 based on the monitored simulatedresponse. By providing simulated signals S1-S4 that simulate variouserror and/or anomaly conditions, such as, for example, defects on thesurface of a CD 50 being played in a CD player 20 of FIG. 1, orsituations in which CD player 80 is exposed to vibration, and bymonitoring the resulting control signals and simulated responses ofsystem components to those control signals, a user of the system 70 candetermine how to optimize system components and/or processing steps andparameters employed in audio/data processing circuitry 30 to improve theresponse of the CD player 20 to anomalies, such as defects in the CDand/or environmental vibrations, or other environmental factors. Thiscan be accomplished without exposing the system 70 to actual defectivedisks or vibrations, and can also be accomplished in an automatedfashion by configuring simulator 60 to sequence through a number of“anomaly” scenarios without user intervention.

FIG. 3 generally illustrates a method 100 for evaluating the response ofoptical digital disk player circuitry to anomalies. In a first step 102of the method 100, an optical digital disk player is provided. In thepresent embodiment, the optical digital disk player is an audio CDplayer configured to play an audio CD. In an alternate embodiment, theoptical digital disk player is a player capable of optically extractingdigital data from an optical digital disk, including, for example,CD-ROM drives, rewritable CD drives, DVD players, and DVD writers.

In a second step 104 of the method 100, an optical digital disk that isan audio CD having anomalies is played in the CD player provided in step102. In the present embodiment, the anomalies are defects on the surfaceof the audio CD that is being played, and include, for example,scratches and/or dirt on the surface of the audio CD. In an alternateembodiment in which an optical digital disk player other than an audioCD player is employed in the method, the optical digital disk havinganomalies may include an audio CD, or an optical digital disk other thanan audio CD, such as, for example, a DVD.

In a third step 106 of the method 100, signals provided by the pickupmechanism of the audio CD player are monitored while an audio CD havinganomalies is being played to identify unique signal characteristics ofthe pickup mechanism associated with the playback of an audio CD havingan anomaly. It should be appreciated that the pickup mechanism signalscan be captured electronically, such as, for example, by a digitaloscilloscope, so that they can be retrieved for later analysis andreview. In an alternate embodiment, the signals provided by the pickupmechanism of an optical digital disk player are monitored while anoptical digital disk other than an audio CD having anomalies is beingplayed to identify unique signal characteristics of the pickup mechanismassociated with the playback of an optical digital disk having ananomaly.

In a fourth step 108 of the method 100, simulator circuitry is coupledto optical digital disk processing circuitry configured to process audioand/or data provided by an optical digital disk player pickup mechanism.In the present embodiment, the optical digital disk processing circuitryis audio CD processing circuitry configured to process audio and/or dataprovided by an audio CD player pickup mechanism.

In a fifth step 110 of the method 100, simulated pickup mechanismsignals are created by the simulator circuitry, such that the simulatedpickup mechanism signals substantially resemble pickup mechanism signalsgenerated by an optical digital disk player playing an optical digitaldisk having an anomaly. In the present embodiment, the simulated pickupmechanism signals substantially resemble pickup mechanism signalsgenerated by an audio CD player playing an audio CD having an anomaly.

In a sixth step 112 of the method 100, the simulated pickup mechanismsignals are provided to the processing circuitry.

In a seventh step 114 of the method 100, the processing circuitry towhich the simulated pickup mechanism signals have been providedgenerates control signals, based on the simulated pickup mechanismsignals. The control signals are configured to control motors and/ormechanisms of optical digital disk players. In the present embodiment,the control signals generated include tracking, focus, sled and motorcontrol signals.

In an eighth step 116 of the method 100, the control signals areprovided to the simulator circuitry. In an alternate embodiment, thecontrol signals are first provided to analog-to-digital convertercircuitry prior to being provided to the simulator circuitry.

In a ninth step 118 of the method 100, the control signals are monitoredby the simulator circuitry to evaluate the response of the processingcircuitry to the simulated pickup mechanism signals.

In a tenth step 120 of the method 100, the simulated pickup mechanismsignals are modified by the simulator circuitry based on the controlsignals.

In an eleventh step 122 of the method 100, the simulator circuitrysimulates the response of a pickup mechanism of an optical digital diskplayer to the control signals. In the present embodiment, the simulatorcircuitry simulates the response of a pickup mechanism of an audio CDplayer to the control signals.

In a twelfth step 124 of the method 100, the simulated pickup mechanismsignals are modified based on the simulated response of the pickupmechanism.

FIG. 4 generally illustrates a method 200 for evaluating the response ofoptical digital disk player circuitry to anomalies. In a first step 202of the method 200, an optical digital disk player is provided. In thepresent embodiment, the optical digital disk player is an audio CDplayer configured to play an audio CD. In an alternate embodiment, theoptical digital disk player is a player capable of optically extractingdigital data from an optical digital disk, including, for example,CD-ROM drives, rewritable CD drives, DVD players, and DVD writers.

In a second step 204 of the method 200, an optical digital disk that isan audio CD is played in the CD player provided in step 202 while the CDplayer is subjected to anomalies. In the present embodiment, theanomalies are physical vibrations introduced into the CD player while itis playing an audio CD. In an alternate embodiment in which an opticaldigital disk player other than an audio CD player is employed in themethod, the anomalies are physical vibrations introduced into theoptical digital disk player while it is playing an optical digital disk.

In a third step 206 of the method 200, signals provided by the pickupmechanism of the audio CD player are monitored while the audio CD playeris subjected to physical vibrations during playback of an audio CD toidentify unique signal characteristics of the pickup mechanismassociated with the playback of an audio CD in the audio CD playerduring exposure to physical vibrations. It should be appreciated thatthe pickup mechanism signals can be captured electronically, such as,for example, by a digital oscilloscope, so that they can be retrievedfor later analysis and review. In an alternate embodiment, the signalsprovided by the pickup mechanism of an optical digital disk player otherthan an audio CD player are monitored while the optical digital diskplayer is subjected to physical vibrations during playback of an opticaldigital disk to identify unique signal characteristics of the pickupmechanism associated with the playback of an optical digital disk in theoptical digital disk player during exposure to physical vibrations.

In a fourth step 208 of the method 200, simulator circuitry is coupledto optical digital disk processing circuitry configured to process audioand/or data provided by an optical digital disk player pickup mechanism.In the present embodiment, the optical digital disk processing circuitryis audio CD processing circuitry configured to process audio and/or dataprovided by an audio CD player pickup mechanism.

In a fifth step 210 of the method 200, simulated pickup mechanismsignals are created by the simulator circuitry, such that the simulatedpickup mechanism signals substantially resemble pickup mechanism signalsgenerated by an optical digital disk player playing an optical digitaldisk during exposure to an anomaly such as a vibration. In the presentembodiment, the simulated pickup mechanism signals substantiallyresemble pickup mechanism signals generated by an audio CD playerplaying an audio CD during an anomaly such as a vibration.

In a sixth step 212 of the method 200, the simulated pickup mechanismsignals are provided to the processing circuitry.

In a seventh step 214 of the method 200, the processing circuitry towhich the simulated pickup mechanism signals have been providedgenerates control signals, based on the simulated pickup mechanismsignals. The control signals are configured to control motors and/ormechanisms of optical digital disk players. In the present embodiment,the control signals generated include tracking, focus, sled and motorcontrol signals.

In an eighth step 216 of the method 200, the control signals areprovided to the simulator circuitry. In an alternate embodiment, thecontrol signals are first provided to analog-to-digital convertercircuitry prior to being provided to the simulator circuitry.

In a ninth step 218 of the method 200, the control signals are monitoredby the simulator circuitry to evaluate the response of the processingcircuitry to the simulated pickup mechanism signals.

In a tenth step 220 of the method 200, the simulated pickup mechanismsignals are modified by the simulator circuitry based on the controlsignals.

In an eleventh step 222 of the method 200, the simulator circuitrysimulates the response of a pickup mechanism of an optical digital diskplayer to the control signals. In the present embodiment, the simulatorcircuitry simulates the response of a pickup mechanism of an audio CDplayer to the control signals.

In a twelfth step 224 of the method 200, the simulated pickup mechanismsignals are modified based on the simulated response of the pickupmechanism.

The invention, as described, advantageously provides methods 100 and200, and a system 70 for evaluating the response of an optical digitaldisk player to anomalies encountered by the optical digital disk playerduring playback of an optical digital disk. The methods and systemaccomplish this by using simulated input signals, rather than byrequiring the use of fragile defect optical digital disks, and ratherthan exposing the optical digital disks and/or optical digital diskplayer to potentially damaging physical anomalies, such as vibration.The method and system also advantageously provide for testing theresponse of optical digital disk players to multiple anomalies withoutrequiring multiple defect optical digital disks to be manually swappedin and out of optical digital disk players. The above advantages canprovide for more efficient, cost-effective testing of optical digitaldisk players.

The above description is considered that of the preferred embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove are merely for illustrative purposes and not intended to limit thescope of the invention, which is defined by the following claims asinterpreted according to the principles of patent law, including thedoctrine of equivalents.

The invention claimed is:
 1. A test system for evaluating the responseof optical digital disk player components to vibration during playbackof an optical digital disk, comprising: a simulator comprising at leastone digital output, said simulator configured to provide a simulateddigital output signal at said at least one digital output simulatingwaveform characteristics provided by a pickup mechanism of an opticaldigital disk player experiencing vibration during playback of an opticaldigital disk; a digital-to-analog converter coupled to said at least onedigital output, said digital-to-analog converter being configured toconvert the simulated digital output signal to a simulated analog outputsignal; and processing circuitry coupled to said digital-to-analogconverter, said processing circuitry being configured to receive thesimulated analog output signal from said digital-to-analog converter,determine the value of at least one control signal to be issued fromsaid processing circuitry based on the value of the simulated analogoutput signal, and provide the at least one control signal as an output;wherein said simulator is a computer comprising logic circuitry andmemory comprising at least one algorithm, and wherein said at least onealgorithm is configured to cause said logic circuitry to provide thesimulated digital output signal.
 2. The test system of claim 1, furthercomprising analog-to-digital converter circuitry coupled to saidsimulator and said processing circuitry, wherein said analog to digitalconverter circuitry is configured to convert the at least one controlsignal provided by said processing circuitry into digital form, andprovide the at least one converted digital control signal to saidsimulator, and wherein said simulator is configured to monitor theconverted digital control signal to evaluate the performance of saidprocessing circuitry.
 3. The test system of claim 2, wherein saidsimulator is further configured to alter the simulated digital outputsignal responsive to the converted digital control signal.
 4. The testsystem of claim 1, wherein said simulator is configured to monitor theat least one control signal to evaluate the performance of saidprocessing circuitry.
 5. The test system of claim 4, wherein saidsimulator is further configured to alter the simulated digital outputsignal responsive to the control signal.
 6. The test system of claim 5,wherein said simulator is further configured to simulate a response ofat least one of a tracking adjustment mechanism, focus adjustmentmechanism, and sled adjustment mechanism of an optical digital diskplayer to the at least one control signal, and generate at least onevalue indicative of the simulated response.
 7. The test system of claim6, wherein said simulator is configured to monitor the at least onevalue indicative of the simulated response to evaluate performance ofsaid processing circuitry.
 8. The test system of claim 7, wherein saidsimulator is further configured to alter the simulated analog outputsignal responsive to the at least one value indicative of the simulatedresponse.
 9. The test system of claim 1, wherein said computer isconfigured to monitor the at least one control signal to evaluate theperformance of said processing circuitry, and is further configured toalter the simulated digital output signal responsive to the at least onecontrol signal.
 10. The test system of claim 1, further comprising anoptical digital disk player simulation algorithm located in the memoryof said computer, said optical digital disk player simulation algorithmconfigured to cause the logic circuitry of said computer to simulate aresponse of at least one of a tracking adjustment mechanism, focusadjustment mechanism, and sled adjustment mechanism of an opticaldigital disk player to the at least one control signal, and generate atleast one value indicative of the simulated response.
 11. The testsystem of claim 10, wherein said computer is configured to monitor theat least one value indicative of the simulated response to evaluate theperformance of said processing circuitry, and is further configured toalter the simulated digital output signal responsive to the at least onevalue indicative of the simulated response.
 12. The test system of claim1, wherein said processing circuitry further comprises audio processingcircuitry configured to process audio data from a pickup mechanism of anoptical digital disk player playing an audio CD to provide an audiosignal.
 13. The test system of claim 1, wherein said processingcircuitry further comprises a digital data output configured to providethe at least one control signal to monitoring circuitry external to saidprocessing circuitry.
 14. A method for evaluating the response of anoptical digital disk player to vibration during playback of an opticaldigital disk, comprising the steps of: coupling simulator circuitry toprocessing circuitry configured to process signals from an opticaldigital disk player pickup mechanism; electronically creating in thesimulator circuitry a simulated anomaly signal simulating anomalywaveform characteristics provided by a pickup mechanism of an opticaldigital disk player encountering vibration during playback of an opticaldigital disk; providing the simulated anomaly signal to the processingcircuitry; and processing the simulated anomaly signal in the processingcircuitry to generate at least one control signal; wherein theprocessing circuitry is configured to process data from an audio CD, andwherein the processing circuitry includes at least one of a skipindicator, mute audio indicator, and output data signal, and furtherincluding the step of monitoring at least one of the skip indicator,mute audio indicator and output data signal to evaluate the response ofthe processing circuitry to the simulated anomaly signal.
 15. The methodof claim 14, further including the step of monitoring the at least onecontrol signal to evaluate the response of the processing circuitry tothe simulated anomaly signal.
 16. The method of claim 15, furtherincluding the step of altering the simulated anomaly signal responsiveto the at least one control signal.
 17. A method for evaluating theresponse of an audio compact disk player circuitry to vibration duringplayback of an audio compact disk, comprising the steps of: couplingsimulator circuitry including logic, memory comprising an algorithm, anda digital-to-analog converter to processing circuitry configured toprocess signals provided by an audio compact disk player; executing thealgorithm in the logic of the signal generating circuitry toelectronically create in the simulator circuitry a simulated anomalysignal simulating waveform characteristics provided by a pickupmechanism of an audio compact disk player encountering vibration duringplayback of an audio compact disk; providing the simulated anomalysignal to the processing circuitry; processing the simulated anomalysignal in the processing circuitry to generate at least one controlsignal; and monitoring the at least one control signal to evaluate theresponse of the processing circuitry to the simulated anomaly signal.18. The method of claim 17, further including the step of altering thesimulated anomaly signal responsive to the at least one control signal.19. A simulator for a media player, wherein the media player comprises apickup mechanism, a control processing circuit, a drive motor, a focusadjustment mechanism, a tracking adjustment mechanism, and a sledadjustment mechanism, and wherein the simulator is configured to:simulate an anomaly signal by generating digital simulated waveformcharacteristics representative of waveforms received from a pickupmechanism of a media player during a disrupted playback event; implementa media player simulation algorithm to simulate a response to processingof the simulated anomaly signal based on one or more control signalsthat are generated by a control processing circuit; and evaluate thesimulated response and adjust the simulated anomaly signal by anadjustment value based on the evaluated simulated response.
 20. Thesimulator of claim 19, wherein the one or more control signal isgenerated by a control signal processing circuit, communicativelycoupled to the simulator, and wherein the one or more control signalincludes at least one of a motor control signal, a focus control signal,a tracking control signal, or a sled control signal.
 21. The simulatorof claim 20, wherein the motor control signal is configured to control aspeed and direction of a drive motor of the media player.
 22. Thesimulator of claim 20, wherein the focus control signal is configured tocontrol a focus adjustment mechanism of the media player.
 23. Thesimulator of claim 20, wherein the tracking control signal is configuredto control a tracking adjustment mechanism of the media player.
 24. Thesimulator of claim 20, wherein the sled control signal is configured tocontrol a sled adjustment mechanism of the media player.
 25. Thesimulator of claim 19, wherein the media player simulation algorithm isfurther configured to cause the logic circuitry of the simulator togenerate the adjustment value.
 26. The simulator of claim 19, whereinthe disrupted playback event is representative of disruptions comprisingat least one of a defective surface of a media and vibration of themedia player.
 27. A simulator for a media player, wherein the mediaplayer comprises a pickup mechanism, a control processing circuit, adrive motor, a focus adjustment mechanism, a tracking adjustmentmechanism, and a sled adjustment mechanism, and wherein the simulator isconfigured to: generate a simulated disrupted signal on a media player;implement a media player simulation algorithm to simulate a response ofat least one of an adjustment mechanism and a spindle drive motor;monitor a control signal generated by a control processing circuit forthe at least one of the adjustment mechanism and the spindle drive motorbased on the simulated and monitored response, and further monitor aperformance response associated with the monitored control signal; andalter the generated simulated signal based on an evaluation of themonitored performance response.
 28. The simulator of claim 27, whereinthe adjustment mechanism comprises a tracking adjustment mechanism, afocus adjustment mechanism, and a sled adjustment mechanism.
 29. Thesimulator of claim 27, wherein the media player simulation algorithm isfurther configured to cause the logic circuitry of the simulator togenerate an adjustment value.
 30. The similar of claim 29, wherein thealtered generated simulated signal is altered by the adjustment value.31. The simulator of claim 27, wherein the simulated disrupted signal isrepresentative of a disruption comprising at least one of a defectivesurface of a media and vibration of the media player.